Lapping machine



Patented Feb. 3, 1 953 LAPPING MACHINE Raymond G. Roshong, North Hollywood, Calif., assignor to Crane Packing Company, Chicago, 111., a corporation of Illinois Application March 21, 1950, Serial No. 150,978

3 Claims. 1

This invention relates to means for rotatably supporting work on a flat abrading tool, such as a lapping plate, while the work is being abraded by the platen.

In a copending application of Earl J. Bullard, Serial No. 14,619, filed March 12, 1948, now Patent No. 2,565,590, dated August 28, 1951, there is disclosed a lapping machine for finishing flat surfaces, the machine incorporating a discshaped platen or lap plate on which are mounted various articles to be abraded, some of which are annular in form. The abrading effect is secured by rotating the platen about its axis and holding the articles to be abraded on the surface in such a manner that the articles rotate about their own axes while their axes are relatively fixed with relation to the frame of the machine. The rotation of the articles is effected by the force of friction between the articles and the lap surface.

In the form shown in the aforesaid Bullard patent, the means for holding the articles relative to the frame of the machine comprise pins extending upward away from the lap surface into slots in cross members of the machine frame. Although this method of holding the articles is entirely satisfactory for light work, it has been found that on heavy work the force of friction is very great and that this force, acting at a considerable distance from the point of support of the pin rotatably holding the article, causes a turning movement about the said point of support. This turning movement is evidenced by a tilting of the article on the lap surface, and the tilting in turn results in a gouging of the lap surface, thereby destroying its usefulness for lapping fiat surfaces.

The principal object of this invention is to provide a means for holding an article on a rotating lap wherein the holding means is located as close to the point of application of the force of friction on the article as it is reasonably possible to place it.

It has also been found that in order to maintain the surface of the lap perfectly fiat indefinitely, it is necessary to locate the articles being lapped relative to the surface of the lap in such a way that the wear of the lap surface is uniform across its entire radial dimension. To accomplish this condition, it is necessary to provide means for shifting the articles radially of the lap to optimum positions and then holding the articles in such positions until the lapping cycle is completed.

It is accordingly another object of this invention to provide a holding means for articles to be abraded on a substantially fiat lapping platen, said means having provision for adjusting the position of the articles relative to the lap surface.

A more specific object of this invention is to provide a holding means for articles to be lapped by a flat lapping platen, said holding means comprising yokes which partially embrace the articles, said yokes being adjustably mounted with respect to the frame of the machine so that they may be moved radially inwardly or outwardly as required to maintain a flat lap.

These and other objects of this invention will become apparent from the following detailed description when taken together with the accompanying drawings, in which Fig. 1 is a plan view of a lapping machine showing the novel supporting means for the article being lapped;

Fig 2 is a fragmentary enlarged section taken through the supporting means of Fig. 1 along line 22 thereof; and

Fig. 3 is a fragmentary enlarged section of the supporting means taken along line 3-3 of Fig. 1.

Referring now to the drawings for a detailed description of the invention there is shown a base casting l9 which constitutes the frame of the lapping machine on which is mounted a tank It containing an abrading compound which is fed by suitable means (not shown) to the articles to be lapped. Projecting outwardly from the surface of base casting Ill is a platen or lap plate I2 having an annular abrading surface [3 interrupted at regular intervals by radially disposed slots [4 which serve to carry away excess abradant as well as the cuttings resulting from the abrading operation. Suitable means (not shown) is provided for rotating platen [2 in the direction of the arrow [5. The surface [3 of the platen l2 may have any desired contour, but for purposes of illustration will be shown as being perfectly flat.

The articles to be abraded chosen for illustration are in the form of rings l6 having an inner diameter which is slightly smaller than the radial dimension of the annular lap surface I3 and an outer diameter which is greater than the said radial dimension of the surface 13 such that the outer edges of ring l6 over hangs the inner and outer edges of the surface 13. Said rings l6 may comprise circular articles being lapped or they may constitute circular holders for articles lBa to be lapped in the manner described in the aforementioned Billiard ar. No. 2,565,590, the latter case usually being articles are relatively small and may be inserted within the rings [6 so as to be retained on the lap surface l3 thereby. When said rings I6 are used as work holders, they also function to maintain the lap perfectly flat and true at all times and in effect compensate for any uneven wear which might result from the abrading action taking place between surface !3 and the articles to be lapped.

In order that the desired lapping operation may take place, it is necessary to hold rings 15 against revolution with platen 62, but they must be free to rotate about their own axes. The holding means, therefore, is comprised of the following elements:

A frame member in the form of a yoke ii having a pair of arms l8 and i3 is disposed adjacent each ring it. Said yoke i? is so formed as to avoid contact with ring l at all points. Mounted on the ends of arms it and 59 are antifriction members or rollers '26 and 2! which contact ring thereby permitting said ring it to rotate about its own axis relative to yoke i'i. ihe location of yoke ii relative to platen i2 is so selected that the resulting force developed between platen i2 and ring it passes between rollers i353 and 2! as diagrammatically indicated by the arrows of Fig. 1.

Yoke ii is held against rotation with platen l2 by means of a bolt 22 passing through a slot 23 in the shank 2 of yoke ll. Said bolt 22 (Figs. 2 and 3) is threaded into a ring 25 which in turn i secured to frame i by any suitable means. For ease of assembly, and in order to hold ring 25 spaced from the surface 25 of frame it, ring 25 is mounted on a plurality of bosses 2'? extending upwardly from surface 26.

To relieve bolt 22 of any torque which might be imposed upon it by the rotation of ring it against yoke i7, 2 is retained between a pair of guides 28 and 2S suitably secured to ring 25. Said guide 23 and 255 permit a sliding action between ring 25 and shank but prevent relative rotation between these elements.

She radial position of each ring !5 may be altered loosening bolt 22 and then sliding the shank 2 5 of yoke ii in guides 28 and 23 until the desired position is obtained, whereupon bolt 22 may then be tightened and ring it will be held in the selected position while it is being operated upon by platen i2.

"ihe,scinewhat raised position of ring 25 relato surface 25 and it continuity about platen i2 causes said ring 25 to function as a guard in the event one of the yokes should inadvertently become fr e of guides 28 and 29. It will be appreciated that the rotation of platen i2 normally tends to carry with it any article resting upon surface :3 and. that if the article is not restrained, it will'be thrown off by centrifugal force. Where such articles are heavy, they be thrown off with suincient foroe to cause a severe accident to operating personnel or damage to equipine; t.

it will be noted that the use yokes I? rcnders the interior of ring it readily accessible by the operator so that if said rings are being used as holc ers, finished articles may be readily removed from the machine and the machine may then be equally as readily reloaded with other articles to be lapped.

It is understood that the foregoing description is illustrative of preferred embodiments of this invention and that the scope of the inven- 4 tion is not to be limited thereto, but is to be determined by the appended claims.

What is claimed is:

1. In a machine for lapping a true surface of predetermined contour upon an article, a stationary machine framework, a lap plate having a lap surface adapted to receive the article thereon and capable of producing the desired surface on the article by relative movement between the lap surface and article, means for rotating the lap plate, said framework including a support positioned adjacent an edge of the lap plate and slightly above the general plane of the lap surface thereof, a generally circular eonditioning ring and article holder loosely positioned on the lap surface and adapted to wear said lap surface upon relative movement between the ring and lap surface, said conditioning ring being adapted. to receive therein an article undergoing lap-ping, a yoke assembly for restraining said conditioning ring against revolution about the vertical axis of rotation of the lap plate while permitting independent rotation of the ring about its own axis, said yoke assembly including a yoke proper having a pair of yoke arms, an antifriction member mounted on each yoke arm, means for securing said yoke to said support in a position wherein said antifriction members closely overlie the plane of said lap plate and engage the outer periphery of the conditioning ring at spaced points therearound and subtend an arcuate increment of the ring therebetween, said antifriction members being so positioned above the plane of the lap plate that the resultant vectorial force exerted upon the ring during rotation of the lap plate is directed between said antifriction members to thus prevent revolution of the conditioning ring about the lap plate axis, said yoke arms each being disposed wholly outside the confines of the conditioning ring when the latter is in position between said antifriction members.

2. In a machine for lapping a true surface of predetermined contour upon an article, a stationary machine framework, a la plate having a lap surface adapted to receive the article thereon and capable of producing the desired surface on the article by relative movement between the lap surface and article, means for rotating the lap plate, a generally circular conditioning ring and article holder loosely positioned on the lap surface and adapted to Wear said lap surface upon relative movement between the ring and lap surface, said conditioning ring being adapted to receive therein an article undergoing lapping, means for restraining said conditioning ring against revolution about the vertical axis of rotation of the lap plate while permitting independent rotation of the ring about its own axis, said means comprising a pair of rollers supported from the framework above the plane of the surface of the lap plate for rotation about respective axes which are substantially parallel to the axis of rotation of the lap plate and positioned to engage the outer periphery of the conditioning ring at spaced regions therearound and subtend an arcuate increment of the ring therebetween so that the resultant vectorial force exerted upon the ring during the rotation of the lap plate due to friction therebetween, is directed between said rollers to thus prevent revolution of the conditioning ring about the lap plate axis.

3. In a machine for lapping a true surface of predetermined contour upon an article, a stationary machine framework, a lap plate having a lap surface adapted to receive the article thereon and capable of producing the desired surface on the article by relative movement between the lap surface and article, means for rotating the lap plate, said framework including a support positioned adjacent an edge of the lap plate and slightly above the general plane of the la surface thereof, a generally circular conditioning ring and article holder loosely positioned on the lap surface and adapted to wear said lap surface upon relative movement between the ring and lap surface, said conditioning ring being adapted to receive therein an article undergoing lapping, a yoke assembly for restraining said 15 conditioning ring against revolution about the vertical axis of rotation of the lap plate while permitting independent rotation of the ring about its own axis, said yoke assembly including a yoke proper having a pair of yoke arms and a shank portion, a roller mounted on each yoke arm, means for adjustably securing said shank portion of the yoke to said support in positions wherein the plane of the rollers closely overlie said lap plate and engage the outer periphery of the conditioning ring at spaced points therearound and subtend an arcuate increment of the ring therebetween and whereby the ring when thus engaged by said rollers may assume different positions radially of the lap plate with the rollers being so located that the resultant vectorial force exerted upon the ring during the rotation of the lap plate is directed between said rollers to thus prevent revolution of the conditioning ring about the lap plate axis, and guide means on said support for said yoke shank portion engaging the latter in any adjusted position thereof to prevent the yoke from turning bodily relative to the support due to the application of torque thereof by said conditioning ring.

RAYMOND G. ROSHONG.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 371,062 Hayes Oct. 4, 1887 522,044 Carlyle June 26, 1894 914,591 Mayer Mar. 9, 1909 970,227 Homan Sept. 13, 1910 1,166,006 Schenkein et al. Dec. 28, 1915 1,420,751 Ricketts June 27, 1922 1,440,639 Smith Jan. 2, 1923 1,476,863 Weaver Dec. 11, 1923 1,515,743 Markland -1 Nov. 18, 1924 1,576,769 Lutz Mar. 16, 1926 2,013,262 Wilsey Sept. 3, 1935 2,209,071 Bullard July 23, 1940 2,274,332 Jarrett Feb. 24, 1942 2,565,590 Bullard Aug. 28, 1951 FOREIGN PATENTS Number Country Date 863,711 France Jan. 6, 1941 

